Apple MacBook Pro with Retina Display (15-inch, 2014) review: Still the best higher-res laptop, but the competition is catching up - CNET
Timetec Hynix IC 8GB Compatible for Apple DDR3L 1600MHz PC3L-12800 SODIMM Memory Upgrade for Early/Mid/Late 2011, Mid/Late 2012, Early/Late 2013, Late 2014, Mid 2015 MacBook Pro, iMac, Mac Mini (8GB) - Newegg.com
Apple MacBook Pro Retina 15 (Mid 2015) Review - NotebookCheck.net Reviews
Timetec Hynix IC 8GB KIT(2x4GB) Compatible for Apple DDR3L 1600MHz PC3L-12800 for Early/Mid/Late 2011, Mid/Late 2012, Early/Late 2013, Late 2014, Late 2015 MacBook Pro, iMac, Mac Mini (8GB KIT(2x4GB)) - Walmart.com
How to use an NVMe drive to upgrade your Mac's SSD | AppleInsider